Erosion and deposition on the eastern margin of the Bermuda Rise in the late Quaternary Academic Article uri icon

abstract

  • A near-bottom survey has been made on the Eastward Scarp (32°50′N, 57°30′W) of the Bermuda Rise, which rises 1150 m above the 5500-m deep Sohm Abyssal Plain in the western North Atlantic. The survey reveals evidence of erosion and deposition at present and in the late Quaternary by the deeper levels of the westward flowing Gulf Stream Return Flow. Four distinct regions of increasing bed gradient show increasing sediment smoothing and scour in the transition from plateau to abyssal plain. Bedforms observed are current crescents, crag and tail, triangular ripples, elongate mounds, transverse mud ripples, lineations, and furrows ranging from 10 to 1 m or less in depth, decreasing generally with bed gradient. Measured near-bottom current speeds are up to 20 cm s-1. Temperature structure on the lower, steep, slopes suggests that detachment of bottom mixed layers may occur there. Extensive net erosion appears to be confined to the lower steep slopes of the scarp. Reflection profiles (4 kHz) show that there has been erosion in areas thinly draped with recent sediments and in areas that show development of small scarps. The distribution of subsurface acoustic characteristics of the region corresponds broadly to the areas characterized by bed gradient and distinct sedimentation conditions. Subsurface hyperbolae, possibly caused by buried furrows, show furrow persistence through several tens of metres of deposition. Erosion occurs up to the top of the scarp during episodes of presumed stronger currents, which may correspond with intensified circulation during glacials. © 1982.

published proceedings

  • Deep Sea Research Part A. Oceanographic Research Papers

author list (cited authors)

  • McCave, I. N., Hollister, C. D., Laine, E. P., Lonsdale, P. F., & Richardson, M. J

citation count

  • 29

complete list of authors

  • McCave, IN||Hollister, CD||Laine, EP||Lonsdale, PF||Richardson, MJ

publication date

  • May 1982